Implantable cardiac leads are well known in the art. They find use, for example, in electrically coupling implantable cardiac monitors and implantable cardiac stimulation devices, such as implantable cardiac defibrillators (ICD's) or implantable pacemakers, to selected chambers of the heart. The leads may include one electrode, an electrode pair, or multiple electrodes, for sensing electrical activity of the heart and/or delivering pacing stimulation pulses to the heart. A lead may alternatively or additionally include one or more electrodes for delivering defibrillation pulses to a heart.
Most often, a patient receiving an implantable cardiac device will receive at least two implantable leads, one lead for positioning an electrode or electrodes in an atrium, and the other lead for positioning an electrode or electrodes in a ventricle of the heart. During the initial implant procedure of the implantable device or during device replacement, it is important for the physician to be able to keep track of the electrode implant locations of the leads.
Prior to the present invention, it has been difficult and time consuming for the physician to keep track of the electrode implant locations of the leads. In many instances, physicians had to rely on serial numbers or lead length values included in the serial numbers, placed upon the leads, to discern whether a lead is implanted in an atrium or a ventricle, for example. Implantable leads are of relatively small diameter, and as a result, the serial numbers placed on the leads have correspondingly small font size making them difficult to read and interpret. Still further, the presence of body fluid, such as blood, makes it even more difficult to read and interpret lead serial numbers. The situation is still further aggravated by the fact that many leads are used in or are designed for use in more than one implant location or chamber of the heart. This makes the serial numbers of such leads unreliable for electrode placement discernment.